Heidenhain's Hematoxylin in Cytological Studies of Penicillium Notatum

The nuclei in the hyphae of Penicillia can be stained with Heidenhain's hematoxylin, which allows their study before and after treatment with different chemicals. Conidia are inoculated on a very thin Czapek-Dox agar film covering a slide. The spores after germinating in a moist chamber can be fixed in Flemming's fluid and stained at various growth stages. The preparations may then be differentiated in 4% iron-alum until the nuclei (2-10 nuclei in normal cells, many more sometimes in induced cells) show full contrast. The preparations can be made permanent by sealing with Canada balsam. For photomicrographical purposes, embedding in glycerol is most suitable.